IMO Shortlist 1967 problem 2
Dodao/la:
arhiva2. travnja 2012. An urn contains balls of
![k](/media/m/f/1/3/f135be660b73381aa6bec048f0f79afc.png)
different colors; there are
![n_i](/media/m/e/c/f/ecf060a8faabbcf3c734f47bb5559433.png)
balls of
![i-th](/media/m/c/9/c/c9cda10a8fe08e48438a9beb485dd409.png)
color. Balls are selected at random from the urn, one by one, without replacement, until among the selected balls
![m](/media/m/1/3/6/1361d4850444c055a8a322281f279b39.png)
balls of the same color appear. Find the greatest number of selections.
%V0
An urn contains balls of $k$ different colors; there are $n_i$ balls of $i-th$ color. Balls are selected at random from the urn, one by one, without replacement, until among the selected balls $m$ balls of the same color appear. Find the greatest number of selections.
Izvor: Međunarodna matematička olimpijada, shortlist 1967